RESUMO
BACKGROUND: Rheumatoid arthritis (RA) is a chronic inflammatory condition that impacts not only the musculoskeletal system but also various other systems in the body, including the cutaneous, ocular, respiratory, cardiovascular, and circulatory systems. MicroRNAs (miRNAs) are a class of naturally occurring and highly conserved transcripts that primarily function in the regulation of gene expression. They accomplish this by facilitating the degradation of messenger RNA (mRNA) or by repressing mRNA translation. miRNAs are well-known regulators of a variety of cellular processes. Therefore, we aimed to detect the impact of miR-155 rs767649 polymorphism on RA activity. METHODS: This case-control study included 66 Egyptian patients with RA who visited Al-Zhraa University Hospital, Internal Medicine Department, Cairo, Egypt, and 50 apparently healthy control subjects matched for age and sex. The participants were subjected to full clinical evaluation, including assessments of the disease activity score (DAS), erythrocyte sedimentation rate (ESR), liver and kidney function, anti-cyclic citrullinated peptide antibody (anti-CCP), and miR-155 polymorphism using real-time polymerase chain reaction (PCR). RESULTS: In the RA group, the majority (98.5%) were female, with a mean age of 43 years, while in the control group, 94% were female, with a mean age of 43.4 years. Comparison of laboratory parameters indicated significantly lower hemoglobin levels, higher ESR, and higher serum creatinine and anti-CCP levels in the RA group than in the control group. The RA group had a significantly higher frequency of TT genotypes and significantly lower frequencies of TA and TT genotypes than the control group. Considering the TT genotype and T allele as references, TA, AA, and TA/AA genotypes in the dominant model; AA in the recessive model; and A allele were significantly associated with protective effects against RA development (p<0.05, odds ratio<1). CONCLUSION: rs767649, the functional variant of miR-155, plays an important role in susceptibility to the increased risk of RA, suggesting that miR-155 can be used as a therapeutic target for the treatment of Egyptian patients with RA.